Lysosomal enzyme release from human neutrophils adherent to foreign material surfaces: enhanced release of elastase...

Neutrophils are the major phagocytic white blood cell present during the acute inflammatory response to cardiovascular medical devices and can become activated to release a wide variety of products that help mediate the overall host response. The purpose of this investigation was to develop an in vitro system to study the release of lysosomal enzymes from neutrophils adherent to biomaterial surfaces. Neutrophils isolated from peripheral human blood were allowed to adhere to different biomaterials and lysosomal enzyme release assessed by monitoring elastase-like activity in the supernatant. The number of adherent neutrophils with intact cytoplasmic membranes was estimated by extracting the cells and quantifying lactate dehydrogenase. Stimulated and non-stimulated neutrophils released significantly different amounts of elastase-like activity depending on the biomaterial surface to which they were adhered. The techniques developed in this study form the basis of an in vitro system for investigating the events associated with neutrophil/biomaterial interactions as well as a method for evaluating the white blood cell response to the materials used in circulatory support devices.